Electronic coding device



May 29, 1956 c. R. DAUM ETAL 2,748,376

ELECTRONIC CODING DEVICE Filed July 15, 1953 2 Sheets-Sheet 1 hvvavraks CLAUaE/RUAUM F055;??- /7! AUEMM/ CH @713 WALTER 0. GA E57'KA A/ M/QTTOENEY RECElVER 7 :V 5 m 9 we 05 6 y 7 G o )T 6 z .E m R 8 mm An E SW 3 -E :n H W H o. u w .o 6 P V C 6 M 7 A0 E .r 7 a t; QM. hm mm Q). 2 w W 9 am 0 m D 7 5 8 C May 29, 1956 c. R. DAUM ETAL ELECTRONIC CODING DEVICE Filed July 15, 1953 2 Sheets-Sheet 2 //VVEN TORS CLAUHE A. 0A UM Wm mn m m R6 1 x0 X Mm T EL nited States Patent '0 ELECTRONIC CODING DEVICE Claude R. Danna and Robert H. Kuemrnich, Boulder, and Walter U. Garstka, Denver, Colo.

Application July 15, 1953, Serial No. 368,242

12 Claims. (Cl. 340-190) (Granted under Title 35, U. S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States for governmental purposes Without the payment to us of any royalty thereon in accordance with the provisions of the act of April 30, 1928 (Ch. 460, 45 Stat. L. 467), 35 U. S. C. 266.

This invention relates generally to a telemetering system and more particularly to a telemetering system which transmits intelligence by patterned pulse signals.

It is frequently desirable to indicate a mechanical or physical change at a distance from the place where the change takes place. For instance, there is a need for an automatic device which may be placed at a remote location to measure rainfall, water level or et cetera, and transrnit to a central station by radio an indication of the quantity measured.

Available coding devices for transforming such intelligence into electrical signals have been mechanically complicated and dependent for their operation on multiple contacts. The consistent and dependable accuracy of the available coding devices under extremes of operating conditions'has been questionable.

An object of this invention is to provide a simple, economical and reliable telemetering system.

Another object of this invention is to provide a coding device having a minimum number of moving parts.

.Another object of this invention is to provide a coding device having very low requirements for power.

Another object of this invention is to provide a coding device having a great stability of operation.

.Another object of this invention is to provide a means for obtaining accurate indications of quantity over a wide range.

Another object of this invention is to provide a means for obtaining accurate indications not materially affected by temperature or humidity variations.

Another object of this invention is to provide a telemetering system in which the indication'is not ambiguous.

Other objects and advantages will appear to those skilled in the art from a consideration of the following specification taken in conjunction with the drawings in which:

Fig. 1 is a top plan view of a coding device embodying the principles of this invention;

Fig. 2 is a front elevational view of the stationary cylinder forming a part of Fig. 1;

.Fig. 3 is a front elevational view of the scanning disc and stepped disc forming a part of Fig. 1;

Fig. 4-is a block diagram of a telemetering transmitter embodying the principles of this invention;

. Fig. 5 is a block diagram of the receiving and indicating components of a telemetering system embodying the principles of this inventionyand 6 is an elevational view of a flag to be used as a substitute for the rotating cylinder in Fig. 1.

In Fig. 1 a scanning disc 10, shown in more detail in Fig. 3, is mounted on shaft 11 which is rotated by motor energy by battery 14.

7 2,748,376 Patented May 29., 1956 'ice A stationary cylinder 17, shown more in detail in Fig. 2, is supported on a base 18 which also supports a socket 19. Socket .19 holds photoelectric cell 16. The anode and cathode of photocell 16 are connected in series with battery 20 and output resistor 21. The output of photocell 16 appears across resistor 21 and is applied to the transmitting channel through a preamplifier. The signal appearing across resistor 21 of Fig. l is applied to the input of the preamplifier 66 of Fig. 4 and then to the radio transmitter 67 to modulate the radio signals transmitted thereby.

Rotatable cylinder 25 is fixed to shaft 26 which is journalled for rotation in bearings 27-28 mounted on base 31. Also fixed to shaft 26 are pulley 29 and gear 30.

A stepped disc 33, more clearly seen in Fig. 3, is mounted on a short shaft 34 which is journalled in bearings 42 and 43. Shaft 34 has fixed thereto a worm wheel 36, shown in dotted lines in Fig. 1 under worm 37. Worm wheel 36 meshes with worm 37 which is fixed to shaft 38. Shaft 38 is journalled in bearings 39 and 40. Shaft 38 also is fixed to gear 41 which meshes with gear 30.

A light source, such as an incandescent lamp 45, is mounted on a base 46 and is energized by battery 14. Also supported by base 46 is a cylinder 47 surrounding the light 45 and open at one side to reflect the light from lamp 45 in the desired direction toward lens 50 Which is s pported by base 51. Lens 56 concentrates the light from lamp 45 to project a bright ribbon of light on scanning disc 16 covering at least the area of the projection of slot 60 of stationary cylinder 17 from inside of spiral 5-2 to extreme outside hole of spiral 56 on scanning disc 10. This projection is shown in dotted lines in Fig. 3.

Stationary cylinder 17 is shown in Fig. 2 in a manner to give a clear view of the linear slot 60 extending from the open end of the cylinder v17 throughout the major portion of its length and parallel to the axis of the rotatable cylinder 25. Cylinder 17 is oriented so that the slot 61) faces the scanning disc 10. The projection of slot 60 on scanning disc 10 is on a plane extending between the centers of shafts 11 and 34 The projection of helical :slot 32 of rotating cylinder 25 is also shown in dotted lines on scanning disc 10 in Fig. 3. it will be noted that helical slot 32 is aligned with the stationary slot 69 to pass light at only one point at any rotational position of the cylinder 25. The length of cylinder 25 is so selected that, in its mounted position, cylinder 25 does not obscure the calibrating holes 53.

Disc 10 has a spiral slot 52 which occupies a sector of the disc which is shown as in Fig. 3 but need not be limited to any specific portion of the disc. Disc '10 also has a series of evenly spaced calibrating holes 53, 54 and 55 arranged in an arc coaxially with the shaft 11 on which disc '10 is mounted. The are on which calibrating holes 53 are arranged has a radius greater than the maximum radius of the spiral 52. The first and last of the calibrating holes, holes 54 and 55, are larger than the other calibrating holes. In the embodiment shown, first and last calibrating holes, 54 and 55, respectively, and 9 intermediate calibrating holes 53 are provided, representing from 0 to 10, inclusive, on the scale used.

:Disc 10 also carries'a series of evenly spaced indexing holes 56 slightly smaller than the calibrating holes 53 and arranged in a spiral, the axis of which coincides with the shaft 11 on which disc '10 is mounted. The minimum diameter of the spiral on which indexing holes 56 are arranged is greater than the radius of the are on which the calibrating holes 53 are arranged. In the embodiment shown each indexing hole 56 is radially positioned midway between two calibratin'g holes 53-55. There is an indexing hole '56 radially positioned between eachadjacent pair of calibrating holes 5354-55 except calibrating holes representing and 1 on the scale.

Stepped disc 33 has a stepped periphery comprising a series of steps 57. Each step 57 consists of an arcuate edge having its center coincident with shaft 34 on which the stepped disc 33 is mounted. The first step 57, which has the largest radius, overlaps the disc 10 to such an extent when step 57' is in registry with slot 60, that it blocks out every one of the indexing holes 56 as they pass the slot 60 of cylinder 17. The second step 57" has the next largest radius. When the shaft 34 is positioned so that step 57 is registered with the slot 60, the step 57 will overlap the disc 1i) sufliciently so that only the first indexing hole 56 will be unblocked as it passes the slot 66. When the shaft 34 is positioned so that the step 57" having the smallest radius is registered with slot 60, the disc 33 will overlap the disc 10 so little that none of the indexing holes 56 will be blocked as they pass the slot 60.

An indicating device which might be used at the central station to transform the coded signals produced by the coding device of Fig. 1 into a readily readable indication is shown in Fig. 5, in which a radio receiver 68 receives the signal transmitted by the radio transmitter 67 of Fig. 4. The radio receiver 68 demodulates the radio signal received and converts it into the pulses as produced by the coding device 65. These pulses are applied to one of the vertical deflecting plates 69 of the cathode ray tube 70. Cathode ray tube 70 also includes an electron gun 71, another vertical deflecting plate 72, a pair of horizontal deflecting plates 73 and 74 and a screen 75. I

A square wave generator 78 is provided which has knobs 79 and 80 for adjusting the frequency and phase, respectively, of the square wave produced. The output of the square wave generator is applied to a sawtooth wave generator 82 which produces a sawtooth wave synchronized with the square wave of generator 78 and having a period equal to one-half the period of the square wave. The square wave produced by generator 78 has positive and negative pulses of equal duration and is also applied to one vertical deflecting plate 72 of the cathode ray tube 70. The sawtooth wave produced by generator 82 is applied to one of the horizontal plates 74 of the cathode ray tube 70. The other horizontal deflecting plate 73 is shown in Fig. 5 as grounded. It Will be understood by those skilled in the art that equal and opposite deflecting waves may be applied to each of the pairs of the deflecting plates 69-72 and 73-74, and that the signal produced at the output of receiver 68 may be combined with the square wave produced by generator 78 before the signals are applied to the vertical deflecting plates 6972.

In the operation of the device described above the light from lamp 45 shines through the opening in the reflecting cylinder 47 and is concentrated by the lens 50 so that a concentrated ribbon of light covers the area of the slot 60 as best seen in Fig. 3. If the disc rotates counterclockwise, light will be passed through the disc 10 by the spiral slot 52 to cause a spot of light to travel from a point near the center of disc 10 toward its periphery successively along a scanning path in registry with the slot 60 and having a length and position determined by the radial extent of slot 52. This scanning path stops short of the calibrating holes 53. This travelling spot of light, however, will be blocked by the rotating cylinder 25 except when it passes the part of the slot 32 which is contiguous to and in registry with the slot 60. As the cylinder 25 is turned by shaft 26 and the pulley 29 (or other means-of rotation), the intersection of slots 32 and 60 will move from one end to the other of the scanning path of the spot of light coming through the slot 52. When the slots 52, 32 and 60 are in alinement,

the light from lamp 45 will impinge upon the photocell 16 to give an output pulse to terminals 22 and 23. It will,

therefore, be seen that the position in time, with respect to some reference point in the rotation of disc 10 of the pulse produced when slots 32, 52 and 60 are in registry, is an indication of the exact rotational position of pulley 29.

As the disc 10 rotates, not only is a pulse produced by the photocell 16 each time slots 32, 52 and 60 are in alinement, but a pulse is also produced each time a calibration hole 53-54-55 passes the slot 60. Since the first and last calibration holes 54 and 55, respectively, are larger than the others, they throw more light on photocell 16 and cause a larger pulse to be produced at output terminals 22-23.

The gear ratio provided by the gears 30 and 41 and by worm 37 and worm wheel 36 is such that one step 57 travels past the slot 60 for each revolution of the shaft 26, as used in the example shown in Fig. 1.

If this coding device were used to give an indication of water level at a remote station, a rope 58, shown in section in Fig. 1, might be passed around the pulley 29. The rope might have a float on one end which would rest on the surface of the water and a weight on the other end to keep the rope taut and to give traction on the pulley. When the water was at its lowest point or at zero on the scale, the rotating cylinder 25 would be in such a position that the slot 32 would coincide with a slot 60 at the extreme inner end of the scanning path near the shaft 11. The stepped disc 33 would be so positioned that its step 57 having the maximum radius would have its edge blocking the section of the slot 60 crossed by indexing holes 56. As the water rises, pulley 29 rotates, rotating cylinder 25 and causing the intersection of slots 32 and 60 to move along the scanning path away from the shaft 11. This causes the pulse produced by the intersection of slots 32, 52 and 60 to occur at successively later times with respect to a reference point in the scanning cycle. During each scanning cycle the calibration holes 535455 will expose eleven calibrating holes, producing ten equal spaces during the half of the scanning cycle when the slot 60 is not in registry with the slot 52. However, there is provided a sufiicient overlap between the start and finish of slot 52 and the large calibrating holes 54 and 55 to give an indication of 0 or 10 on the scale.

When the pulley 29 has made one complete revolution the slot 32 will cease to intersect the slot 60 at its outer end and will begin to intersect the slot 60 at its inner end again. At this instant the stepped disc 33 will have rotated counterclockwise until the second step 57" is in registry with the slot 60. This will unblock the first index hole 56' as it crosses the slot 60 and cause an indexing pulse to be made midway between the calibrating holes indicating 1 and 2 on the unit scale. For each further revolution of the pulley 29, another indexing hole 56 will be unblocked by the stepped disc 33 to provide another indexing pulse.

The pulses provided by the coding device might be transmitted by radio to a receiver at a central station, such as that shown in Fig. 5, where they will appear as vertical pulses on screen 75. At the central station the frequency of square wave generator 78 is adjusted by manipulation of the frequency knob 79 until the pulses indicated 'on the screen of the cathode ray tube 70 stand still. At this adjustment the frequency of square wave generator 78 will be such as to provide two displaced time bases 76 and 77. The phase of the square wave 78 is then altered by manipulation of knob 80 until the two large pips 83' and 83", produced by the calibration holes 54 and 55 appear at either end of one of the displaced traces 76 and 77 on the screen. When large pips 83 and 83" are at either end of the time bases, the intermediate calibrating pips 83 will be evenly spaced and spread along the trace between the pips 83 and 83". This will cause the pip 92, produced by the intersection of slots 32, 52

and 60, to appear on the other trace 77.

A number of indexing pips 86, distinguished by size,

l 44 HIM. 4

will appear midway between the calibrating pips 83 and the number of indexing pips 86 will depend upon the rotational position of stepped disc 33 which will, in turn, depend upon the arithmeticaltotal of rotations the shaft 26 has made in a plus and minus direction in arriving at its present positon.

It will be obvious that the display on the screen 75 as shown in Fig. 5, indicates that the pulley 29 has made four revolutions as the float, mentioned above, has risen above the zero mark. This is indicated because there are four indexing pips 86 appearing between the calibration pips 83, representing 1 through 5 on the scale. The position of the pip 92 produced by the intersection of slots 32, 52 and 60, appearing on the trace 77, indicates that the pulley has gone through approximately .65 revolutions since the last index hole was uncovered. If the pulley is a foot in circumference, this indicates that the water is at present 4.65 feet above the zero reference level. Scale marking numbers -10 indicated by reference numeral 93 may be marked under time base 76 to mak'e reading. of the indication more easy. A standard calibrated grid-screen on an oscilloscope may be used as a scale for reading the indication. For more accurate reading the horizontal trace may be elongated so that pip 92 and its two adjacent pips 83 cover the entire chosen scale.

Although the manner of displaying the pulses shown in Fig. is a preferred method, since it eliminates all possibility of confusion, a simpler method can be used in'which the use of the square wave generator 78 is eliminated along with the displacement of the two time bases 76 and 77. With this latter method of display the traces 76 and 77 would be superimposed and the pip 92 would appear on the same base as the pips 83 and 86 representing the calibration and index holes. When a single base line is used, all confusion may be eliminated by arranging the width of slot 52 of rotating disc so that vernier pip 92 will distinguish by its size from calibrating pips 83 and indexing pips 86. However, even though a single base line be used and intermediate calibrating pips 83, indexing pips 86 and Vernier pip 92 all be of the same size, confusion in recognizing the characters of the various pips would only result if the pip 92 appeared midway between the next two calibrating pips after the pair of calibrating pips 83 containing the last index pip 86, or alternately, if pip 92 were directly superimposed upon one of the pips 83 or 86. In practice it is found that the two sweeps on the oscilloscope will never be aligned completely and it is not difiiculty to distinguish between the vernier pip 92 and the calibrating pip 83.

In another alternate embodiment'the large calibrating pips might be used to automatically synchronize the square wave generator 78 with the scanning disc 10, eliminating the necessity for manually adjusting the frequency and phase of generator 78. It will also be obvious that it is only necessary to provide one calibrating pip 83, such as the first pip 83' with a distinguishing characteristic.

Since the index pips 86 show the approximate positions of the level being measured, and since pip 92 shows the fraction of the next unit which indicates the exact level being remotely transmitted, pip 92 might be called a vernier pip and the pulse produced by the intersection of slots 52, 32 and 60 might be called the Vernier pulse.

Fig. 6 shows a flag 95 which may be substituted for the rotatable cylinder 25 in Fig. 1. Flag 95 has a narrow, elongated portion 96, in one end of which is a hole 99 and on the other end of which is a wide portion 97 containing a slot 98 arranged on a spiral about the axis of hole 99. The midsection of narrow, portion 96 is provided with an elongated hole 100.

Where angular motion is to be indicated, such as the amount of opening of a radial type gate, it may be advantageous to use the flag 95 in place of the rotatable cylinder in the device of Fig. 1. In use, the flag 95 would be pivoted through hole 99 at a fixed point in line with statance from shaft 11 that slot 98 of flag 95, on being moved through its complete angle, will sweep past the same portion of slot 60 as was hereinabove described for slot 32 of rotatable cylinder. In this use of flag the position of the pip caused by the registry of slots 52, 60 and 98 will indicate the entire angle to be telemetered. The indexing pips would not be used.

The embodiment of this invention shown in Figs. 1 and 3 transmits the Vernier pip during one half of each rev'olution of disc 1% and the calibrating and indexing pips during the other half. It will be understood that an alternative embodiment could have the spiral slot 52 confined to one sector of the disc 10 and the indexing and calibrating holes confined to another 120 sector to allow any other additional information to be transmitted during the time represented by the remaining 120 sector.

Rotating flexible belts could be used in place of the disc 10 and the rotating cylinder 25. The light source and the phototube could be eliminated, iron slugs being. used in place of the holes in disc 10 and iron wire being used in place of the slots 52, 32 and 60 in discs 10, 25 and 17, respectively. The stepped disc 33 would then be a magnetic shield made of iron and an electromagnet would be used as the responsive device in place of the phototube 16.

It will be seen that this invention provides a particularly advantageous telemetering system with few moving parts, no moving contacts, low power requirements, and no exact limitation on the speed of disc 10. The receiving device at the central station is largely composed of conventional components.

It will be understood that the specific embodiments of this invention described above are exemplary only. Many modifications will occur to those skilled in the art within the scope of the appended claims.

What is claimed is:

1. In combination plane spiral means, means for rotating said spiral means at a substantially constant rate of speed about the axis of said spiral, helical means mounted adjacent to said spiral and on an axis at right angles to the axis of said spiral, means for angularly positioning said helical means in accordance with certain intelligence, a stationary cylinder having a linear slot on a predetermined plane including the axes of the spiral means and the helical means, and light responsive means for producing an indication when any part of said spiral means and any part of said helical means coincides on the predetermined plane.

2. The combination of claim 1 in which there is fixed to and rotating with said spiral means, evenly spaced means for providing calibrating indications as each spaced means coincides with said predetermined plane.

3. The combination of claim 1 in which there is fixed to and rotating with said spiral means spaced indexing means arranged in a second spiral the axis of which is coincident with the axis of said first spiral means, said index means being arranged to give an indication as each of said index means passes said predetermined plane, a stepped member to prevent any of said index means further from the axis than a selected one of said index means from causing an indication, and means for moving said stepped means in accordance with intelligence.

4. The combination of claim 3 in which there is also fixed to and rotating with said spiral means, spaced calibrating means arranged in an arc about the axis of said spiral means and positioned between said spiral means and said indexing means, said calibrating means being arranged to give an indication as each of said calibrating means passes said predetermined plane.

5. The combination of claim 3 in which the first and last of said calibrating means are of different size than the other calibrating means to provide distinguishing characteristics.

6. The combination of claim 3 in which the spiral means extends over no more than 180 about its axis and in which the indexing means extend over no more than 180 about the same axis and in which the sectors containing said spiral means and said indexing means are not to any extent coincident.

7. In combination a plurality of evenly spaced indexing means arranged in a plane spiral about an axis, means for rotating said indexing means about said axis, responsive means for producing an indication when any of said indexing means crosses a predetermined plane, a stepped member arranged to prevent any of said spirally spaced means further from the axis than a selected one of said spaced means from causing an indication, and means for moving said stepped means in accordance with intelligence.

8. The combination of claim 7 in which there are fixed to and rotating with said indexing means evenly spaced calibrating means arranged to give an indication on crossing said predetermined plane.

9. In combination, a disc mounted on an axial shaft and having a spiral slot therein, a motor for rotating said disc at a substantially constant speed, a light source on one side of said disc and a light-responsive element on the other side of said disc, a rotatable cylinder having a helical slot therein, means to rotate said cylinder in accordance with the magnitude of a certain quantity to be measured, a stationary cylinder having a linear slot parallel with the axis of said stationary cylinder, said cylinders being coaxially mounted with the light-responsive means being substantially at the axis of the cylinders.

10. The combination of claim 9 in which said disc has a number of indexing holes arranged in a spiral coaxial with said spiral slot and in which there is provided a rotatable stepped shutter mounted between said indexing holes and said light source, and in which means are provided to rotate said stepped shutter at a rate which is in a predetermined relation to the rate at which the rotatable cylinder is rotated, said cylinders being displaced so that the surfaces of both are between the spiral slot and the light-responsive means but only the surface of the stationary cylinder is between the indexing and calibrating holes and the light-responsive means.

11. The combination of claim 10 in which calibrating means are synchronized with said scanning means and affect said responsive means at uniform intervals, said shutter means being absent from between said responsive means and said calibrating means.

12. The combination of claim 10 in which there are included indexing spot-producing means producing indexing spots to which the responsive means is responsive, said indexing means being synchronized with said scanning means and being arranged to produce spots affecting said responsive means at uniform intervals but at different positions in an extension of said scanning line, stepped shutter means for blocking certain of said scanning spots from said responsive means and means for moving said stepped shutter.

References Cited in the file of this patent UNITED STATES PATENTS Oberrnaier July 22, 1952 

